Engine noise, what could it be?

Just today when I got to work I noticed a somewhat loud noise coming from the engine. I wouldn't have noticed it had the track no changed on my CD. I stopped the music and let it idle and then revved the engine. The sound is RPM dependent but it does not get louder. Oil pressure has not dropped at all. It did not make the noise when I left home this morning. It does have lifter tick since I changed the oil when I first got it a few months ago but this is a lot louder. Do you think it could be a pulley? I just hope it isn't a spun bearing.

EDIT: I just went out and started the car and let it run for about 30 seconds and nothing but the usual lifter tick so it doesn't do it when cold. I'll see if it makes it when I get home tonight.

I dont think a pully would make a noise louder than a lifter tic. When its a spun bearing and you rev up the engine, the noise goes louder as you go up. but since you did a edit, it does not sound like a spun bearing.

Also, it didn't make it when I got home. I did drive through a large puddle when I pulled into work? :dunno:

i wouldn't worry about the sound until it comes back (IF it ever comes back).

Yeah, still not back this morning. Perhpas water got on something on the rotating assembly causing the sound. Scared the crap out of me all day yesterday.

Doesn't sound like a spun bearing. If that was the case it will start to idle terribley and give you trouble starting sometimes too (when it starts to really get bad). Whatever it is, best of luck.

The AC pulleys on these cars are notorious about slinging the bolts off the AC clutch asembly... and makeing it rattle a bit. But it wouldnt have gone away.

i wouldn't worry about the sound until it comes back (IF it ever comes back).

Well, it's back.

It doesn't seem to make it when it is cold and it can come and go after the engine is warmed up. I can't hear it over the radio, but it is pretty apperant if the radio is off. It almost sounds like a deisel engine. I am worried as hell about a spun bearing, but why would it come and go. It should make it all the time if it were a spun bearing. It just seems too loud to be just the lifters.

Needless to say I'm VERY worried right now.

If it was a spun bearing it would be constant. Did you ever check the AC clutch assembly? because mine had the same thing going on and that was what it was. The lifters can get pretty loud espicially if they are geting minimum oil. Get a stethascope and try to find out if the sounds is coming from the block or the heads or even something else.

Hehehe, yeah, that's the only thing helping me sleep at night. Anyhow, I'll check the A/C clutch tonight when I get home. Your comment about the oil got me thinking. It is currently 32° F outside here in Utah. I am running a crap OEM filter and Mobile 1 15w50 synthetic. Perhpas the oil is just too heavy? I have a Mobile 1 filter and some Mobile 1 5w30 for my next oil change but it has less than 2,000 miles on this oil change. Maybe I should change it this weekend regardless.

You don't think the water pump bearing could make this noise do you?